1. Field of the Invention
The present invention relates to microelectromechanical systems (MEMS) processing technology, and more specifically, it relates to embodiments of contact stress/pressure sensors formed by MEMS processes.
2. Description of Related Art
Many industrial applications and research projects require the stress normal to contacting surfaces to be known. Several examples include: designing rollers, designing gaskets and seals, robotic tactile sensors, prosthetics, shoes, surgical instruments, automotive crash tests, brake pads and cartilage studies. There are currently three methods for determining the stresses between contacting surfaces: analytic calculation, computational methods and direct measurement (1). General contact problems are very difficult to solve analytically as geometries and material properties are typically complex and not necessarily known. If these characteristics are known, complex shapes and irregular and changing contact areas are extremely difficult to model. Additionally, deformation of contacting surfaces introduce non-linearities that typically make analytic approaches very difficult or impossible to solve. Computationally, among solid stress/strain modeling efforts, contact problems are considered the most difficult to model. Similar to analytic methods, modeling of complex and/or compliant surfaces is a very difficult and computationally intensive problem. Very large deformations and slip between surfaces add further difficulty for Finite Element Analysis (FEA). Even when it can be used, FEA benefits from direct measurement of contact stress for model validation. Due to the difficulty or impossibility of predicting contact stresses by analytic or computational methods, direct measurement of contact stress is often the only means by which they may be known. Thus, a distinct and very broad need for measurement instrumentation exists. Despite the widespread need for contact stress measurement instrumentation, great progress remains to be made towards the development of contact stress sensors.